"This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken," said Schneider, Williams' third wife, in a statement obtained Monday by the Associated Press.
She asked for privacy on behalf of the family, adding, "As he is remembered, it is our hope the focus will not be on Robin's death, but on the countless moments of joy and laughter he gave to millions."
Williams and Schneider, a graphic designer, were married nearly three years ago, in October 2011. The two met before he had heart surgery in 2009, and she helped him with his convalescence. She was his third wife.
Daughter Zelda Williams tweeted a quote Monday from "The Little Prince" by Antoine de Saint-Exupery in memory of her dad.
"You -- you alone will have the stars as no one else has them ... In one of the stars I shall be living. In one of them I shall be laughing. And so it will be as if all the stars were laughing, when you look at the sky at night ... You -- only you -- will have stars that can laugh," the passage reads.
"I love you. I miss you," the 25-year-old wrote. "I'll try to keep looking up. Z."
Robin Williams' final social media post, sent July 31, was a birthday wish to Zelda that included a photo of father and daughter together when she was young.
The comedian and actor is also survived by Zachary Williams, his 31-year-old son with first wife Valerie Velardi, and Cody, his 22-year-old son with second wife Marsha Garces, who's also Zelda's mom.